Impacts of implementing a corrosion control strategy on biofilm growth

Abstract

Biofilm growth and corrosion are interrelated processes in a drinking water distribution system. The presence of corrosion tubercles alters the quality of the water in many ways, such as increasing the number of available attachment sites on the walls of the pipes for bacteria. Moreover, the presence of corrosion by-products significantly reduces chlorine disinfection and the efficiency of biofilm control. This study is aimed at evaluating the effect of implementing a corrosion control program on the development of biofilm on distribution system pipe walls. No impacts were found during full-scale experimentation, however the results of a pilot-scale study carried out with annular reactors showed that, both in the presence and absence of corrosion by-products, the anti-corrosion chemicals tested (orthophosphates, a blend of ortho-polyphosphates, and sodium silicates) had no impact on biofilm development at the concentrations tested. Higher numbers of bacteria fixed on the walls of the reactors wereassociated with larger corrosion deposits on the annular reactors. Removing these corrosion deposits may have a positive impact on biofilm control in a distribution system.